Heat sink

ABSTRACT

[Task] To improve the cooling efficiency of a heat sink without increasing the size of the heat sink. 
     [Means for solution] A heat sink  1  includes a plurality of coolant passage  2, 3,  and a connecting passage  4  connecting the coolant passages  2, 3  nonlinearly. A height of a fluid passage of the connecting passage  4  on an inflow side to which the coolant flows in is made greater than a height of the coolant passage  2  connected with the fluid passage on the inflow side. On the other hand, the height of the fluid passage of the connecting passage  4  is decreased to an end portion of the connecting passage  4  on an outflow side from which a cooling water flows out. In increasing the height of the fluid passage of the connecting passage  4  on the inflow side to which the cooling water flows in, gradually, the height of the connecting passage  4  is increased so as to equalize the height of a widthwise direction of the fluid passage of the coolant passage  2.

TECHNICAL FIELD

The present invention relates to a heat sink. More specifically, the present invention relates to a heat sink to be equipped in an inverter.

BACKGROUND ART

A heat sink is a device to cool an object to be cooled such as electronic component. Specifically, a water-cooled heat sink arranged to cause a cooling water to flow inside the heat sink is advantageous in capability of stable cooling, and insusceptibility to temperature in an apparatus, as compared to an air-cooled heat sink.

FIG. 5 is an exploded perspective view showing a water-cooled heat sink disclosed in a patent document 1.

This water-cooled heat sink 20 includes a middle plate of metallic material, shaped in the form of a flat plate having an open portion 19, and sandwiched between an upper plate 12 and a lower plate 14 so as to form a fluid passage for a cooling water. Inner fins 15, 16 and 17 are disposed in the open portion 19 of the middle plate 13.

Upper plate 12 is adapted to be provided with a component (not shown) to be cooled. The component is cooled by transfer of heat of the component, through upper plate 12 and inner fins 15, 16 and 17, to the cooling water of a lower temperature for heat exchange.

PRIOR ART LITERATURE Patent Document

Patent Document 1: JP 2008-235725 A.

SUMMARY OF THE INVENTION Problem to be solved by the Invention

In the heat sink to cool a component to be cooled by circulating a cooling water, the cooling efficiency of the water-cooled heat sink becomes lower when the cooling water is unable to flow smoothly, and when the flow of the cooling water is deviated.

In the example of the water-cooled heat sink 20 of the patent document 1, as shown in FIG. 5, the flow of the cooling water is not smooth near a parting portion 22 in a U turn portion of the fluid passage of heat sink 20, and the pressure loss becomes great in the U turn portion.

Therefore, as shown in FIG. 6, the water-cooled heat sink 20 of the patent document 1 is formed to have a structure including stepwise guide grooves or recesses 23, 24 formed in the U turn portion where the cooling water turns so that the cooling water can flow smoothly and easily into the inner fin 16 near the parting portion 22. This structure can improve the heat exchange efficiency of the inner fin 16 by causing the cooling water to flow uniformly into the inner fin 16.

Moreover, in the patent document 1, as shown in FIG. 6, the U turn portion is shaped to have an end portion 21 projecting or bulging outwards so as to ensure a depth or length, and thereby to reduce the pressure loss.

However, the expansion of the volume of the fluid passage of the water-cooled heat sink in the depthwise or lengthwise direction is disadvantageous to the size reduction of the water-cooled heat sink.

Therefore, in a heat sink according to the present invention comprising a plurality of coolant passages and a connecting passage connecting the coolant passages nonlinearly, a height of a fluid passage of the connecting passage on an inflow side to which a coolant flows in is made greater than a height of the coolant passage connected with the fluid passage on the inflow side; and

wherein the height of the fluid passage of the connecting passage is decreased to an end portion of the connecting passage on an outflow side from which the coolant flows out from the connecting passage.

Effect of the Invention

The invention as mentioned above can contributes to improvement of the cooling efficiency of the water-cooled heat sink without increasing the size of the heat sink.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a heat sink according to embodiments of the present invention.

FIG. 2A is a top view of a heat sink according to an embodiment 1 of the present invention. FIG. 2B is an A-A sectional view of the heat sink according to the embodiment 1 of the present invention. FIG. 2C is a B-B sectional view of the heat sink according to the embodiment 1 of the present invention. FIG. 2D is a C-C sectional view of the heat sink according to the embodiment 1 of the present invention.

FIG. 3A is a top view of a heat sink according to an embodiment 2 of the present invention. FIG. 3B is an A-A sectional view of the heat sink according to the embodiment 2 of the present invention. FIG. 3C is a B-B sectional view of the heat sink according to the embodiment 2 of the present invention. FIG. 3D is a C-C sectional view of the heat sink according to the embodiment 2 of the present invention.

FIG. 4 is a top view of the heat sink provided with a fin according to the embodiment 1 of the present invention.

FIG. 5 is an exploded perspective view of a water-cooled heat sink according to an earlier technology.

FIG. 6 is an enlarged view showing a U turn portion of the water-cooled heat sink having a U-shaped fluid passage according to the earlier technology.

MODE FOR CARRYING OUT THE INVENTION

The present invention relates to a heat sink which comprises a plurality of coolant passages and a connecting passage connecting the coolant passages nonlinearly.

A heat sink according to the present invention is configured to restrain the pressure loss in the connecting passage by setting a height of a fluid passage of the connecting passage on an inflow side to which a coolant flows in, greater than a height of the coolant passage causing the coolant to flow into the connecting passage.

In this way, the arrangement making greater the height of the connecting passage on the inflow side to which a coolant flows in, is effective for eliminating the need for increasing the width (depth) of the fluid passage, and avoiding a size increase of the heat sink.

Moreover, the height of the fluid passage of the connecting passage is decreased gradually to an end portion of the connecting passage on an outflow side from which the coolant flows out from the connecting passage. Therefore, it is possible to cause the coolant to flow uniformly from the connecting passage to the coolant passage connected on the downstream side of the connecting passage.

The thus-constructed heat sink according to the present invention can improve the cooling efficiency without increasing the size of the heat sink. The following embodiments of the present invention relate to water-cooled heat sing. However, the coolant according to the present invention is not limited to water.

Embodiment 1

The following is detailed explanation on a water-cooled heat sink according to an embodiment 1 of the present invention with reference to FIG. 1 and FIG. 2 (FIGS. 2A˜2D).

As shown in FIG. 1, the water-cooled heat sink 1 according to the embodiment 1 of the present invention has a structure including a coolant passage 2 and a coolant passage 3 which are connected in the U-shaped form by a connecting passage 4. A parting portion 7 is formed by the coolant passage 2 and 3 and connecting passage 4 connected in the U-shaped form.

One end of the coolant passage 2 is connected with the connecting passage 4 to communicate with the coolant passage 2. The other end of the coolant passage 2 is connected with a coolant inlet pipe or piping 5.

One end of the coolant passage 3 is connected with an outflow side end of the connecting passage 4 from which the coolant flows out from the connecting passage 4. The other end of the coolant passage 3 not connected with the connecting passage 4 is connected with a coolant outlet pipe or piping 6.

In FIG. 1, the coolant passages 2 and 3 are in the form of a plate like tubular member. However, the shape of the coolant passage 2 and 3 according to the present invention is not limited to this, and it is possible to employ an appropriate tubular form.

It is optional to connect another heat sink 1 or another coolant passage by connecting a connecting passage similar, in shape to the connecting passage 4, with the end of the coolant passage 3. In this example, the coolant passage 3 is arranged in parallel to the coolant passage 2 in the same plane. However, it is possible to set the position of the coolant passage 3 arbitrarily.

As shown in FIG. 2B, a component 8 to be cooled is disposed near the heat sink 1 so that heat is transferred from the component 8 to the cooling water flowing in the coolant passage 2 or 3 to exchange heat. As shown in FIG. 2A, the cooling water used for the heat exchange flows from the inlet pipe 5 into the coolant passage 2, flows, through the connecting passage 4 and the coolant passage 3, and flows to the outside from the outlet pipe 6.

As shown in FIG. 2B, the fluid passage height, or the height of the fluid passage, of the connecting passage 4 on the inflow side or upstream side to which the cooling water flows in is set higher than the height of the coolant passage 2. As shown, the height of the fluid passage of the connecting passage 4 on the inflow side to which the cooling water flows in is increased gradually from a connection portion 4 a between the connecting passage 4 and the coolant passage 2. In the vicinity of the connecting passage 4, the fluid passage height, or the height of the fluid passage, of the coolant passage 2 is increased gradually toward the connecting passage 4.

In forming the connecting passage 4 so that the height of the fluid passage of the connecting passage 4 is increased gradually on the cooling water inflow side, the flow speed of the cooling water flowing from the coolant passage 2 into the connecting passage 4 becomes constant or uniform between the left side and right side of the fluid passage if the height of the passage of the connecting passage 4 is increased so as to equalize the height in a widthwise direction of the fluid passage from the connection portion 4 a between the connecting passage 4 and the coolant passage 2. Similarly, in forming the coolant passage 2 so that the height of the fluid passage of the coolant passage 2 is increased gradually, the flow speed of the cooling water flowing in the coolant passage 2 becomes constant or uniform between the left side and right side of the fluid passage if the height of the fluid passage of the coolant passage 2 is increased so as to equalize the height in a widthwise direction of the fluid passage to the connection portion 4 a between the connecting passage 4 and the coolant passage 2. Therefore, this configuration can restrain the pressure loss in the connecting passage 4, and cause the cooling water to flow uniformly in the coolant passage 2.

On the upper surface of the coolant passage 2, the component 8 to be cooled is disposed as shown in FIG. 2B and FIG. 2C. Therefore, the arrangement in which the connecting passage 4 is enlarged in the heightwise direction does not prevent the size reduction of the heat sink 1.

Moreover, as shown in FIG. 2D, the passage height of the connecting passage 4 is decreased from a middle portion 4 b in the flow direction of the connecting passage 4, to a downstream end 4 c from which the cooling water flows out. The position from which the height of the connecting passage 4 is decreased is not limited to the middle portion 4 b, but the position can be set at any point in the longitudinal direction of the connecting passage 4 from the coolant passage 2 to the coolant passage 3. The connecting passage 4 narrowed in this way is effective for equalizing the pressure loss in the fluid passage from the middle portion 4 b in the flow direction in the connecting passage 4, to the end portion 4 c on the outflow side from which the cooling water flows out, and for uniformizing the flow of the cooling water flowing into the coolant passage 3.

In forming the connecting passage 4 so as to decrease the height of the fluid passage of the connecting passage 4, the shape of the connecting passage 4 is not limited to the examples of this embodiment. It is optional to set the shape appropriately to uniformize the flow of the cooling water flowing into the coolant passage 3. The flow of the cooling water flowing from the connecting passage 4 into the coolant passage 3 is difficult and not smooth near the parting portion 7 in the coolant passage 3 because of momentum of the cooling water flowing from the connecting passage 4. Accordingly, the flow of the cooling water in the coolant passage 3 is uniformized by setting the shape of the fluid passage so as to equalize the pressure loss in the fluid passage from the middle portion 4 b of the connecting passage 4 in the flow direction toward the end portion 4 c on the outflow side from which the cooling water flows out of the connecting passage 4.

Embodiment 2

A heat sink according to an embodiment 2 of the present invention is different in the shape of the fluid passage of the connecting passage from the heat sink 1 according to the embodiment 1. Components of the heat sink according to the embodiment 2 similar to the corresponding components in the heat sink of the embodiment 1 are given the same reference numerals, and detailed explanation is omitted and not repeated.

As shown in FIG. 3A, a water-cooled heat sink 10 according to the embodiment 2 of the present invention has a structure including a coolant passage 2 and a coolant passage 3 which are connected in the U-shaped form by a connecting passage 11. A parting portion 7 is formed by the coolant passage 2 and 3 and connecting passage 11 connected in the U-shaped form.

One end of the coolant passage 2 is connected with the connecting passage 11 to communicate with the coolant passage 2. The other end of the coolant passage 2 is connected with a coolant inlet pipe or piping 5.

One end of the coolant passage 3 is connected with the fluid passage of the connecting passage 11 on an outflow side from which the coolant flows out from the connecting passage 11. The other end of the coolant passage 3 not connected with the connecting passage 4 is connected with a coolant outlet pipe or piping 6.

It is optional to connect another heat sink or another coolant passage by connecting a connecting passage similar in shape to the connecting passage 11, with the end of the coolant passage 3. In this example, the coolant passage 3 is arranged in parallel to the coolant passage 2 in the same plane. However, it is possible to set the position of the coolant passage 3 arbitrarily.

As shown in FIG. 3B, a component 8 to be cooled is disposed near the heat sink 10 so that heat is transferred from the component 8 to the cooling water flowing in the coolant passage 2 or 3 to exchange heat. As shown in FIG. 3A, the cooling water used for the heat exchange flows from the inlet pipe 5 into the coolant passage 2, flows, through the connecting passage 4 and the coolant passage 3, and flows to the outside from the outlet pipe 6.

As shown in FIG. 3B, the height of the connecting passage 11 on the inflow side or upstream side to which the cooling water flows in is set higher than the height of the coolant passage 2. As shown, the height of the connecting passage 11 on the inflow side to which the cooling water flows in is increased gradually from a connection portion 11 b between the connecting passage 11 and the coolant passage 2. In the vicinity of the connecting passage 11, the height of the coolant passage 2 is increased gradually toward the connecting passage 11.

On the upper surface of the coolant passage 2, the component 8 to be cooled is disposed. Therefore, the arrangement in which the connecting passage 11 is enlarged in the heightwise direction is not harmful to the size reduction of the heat sink 10.

In forming the connecting passage 11 so that the height of the connecting passage 11 is increased gradually on the cooling water inflow side, the height of the connecting passage 11 is increased so as to equalize the height in a widthwise direction (a direction of an arrow E shown in FIG. 3C), and at the same time the fluid passage of the connecting passage 11 lying on an extension of the coolant passage 2 is formed so as to curve upwards in the heightwise direction of the connecting passage 11. From a connection portion 11 b between the coolant passage 2 and the connecting passage 11 to an upper end 11 a of the connecting passage 11 to which the cooling water impinges, the cross section of this fluid passage is substantially equal to the cross section of the fluid passage of the coolant passage 2. This configuration can made constant or uniform, the flow speed of the cooling water flowing from the coolant passage 2 up to the upper end 11 a of the connecting passage 1, and cause the cooling water to flow uniformly in the connecting passage 11.

Moreover, as shown in FIG. 3D, the height of the fluid passage of the connecting passage 11 is decreased from a middle portion 11 c in the flow direction of the connecting passage 11, to a downstream end 11 d on the outflow side from which the cooling water flows out. The position from which the fluid passage height of the connecting passage 4 is decreased is not limited to the middle portion 11 c, but the position can be set at any point in the longitudinal direction of the connecting passage 11 from the coolant passage 2 to the coolant passage 3. The connecting passage 11 narrowed in this way is effective for equalizing the pressure loss in the fluid passage from the middle portion 11 c in the flow direction in the connecting passage 11, to the end portion 11 d on the outflow side from which the cooling water flows out, and for uniformizing the flow of the cooling water flowing into the coolant passage 3.

The shape of the connecting passage 11 is not limited to the example of this embodiment. It is optional to set the shape appropriately to uniformize the flow of the cooling water flowing into the coolant passage 3. The flow of the cooling water in the coolant passage 3 is uniformized by setting the shape of the fluid passage so as to equalize the pressure loss in the fluid passage in the flow direction from the middle portion 11 c of the connecting passage 11 toward the end portion 11 d on the outflow side from which the cooling water flows out of the connecting passage 4.

As explained in detail above by the use of the embodiments 1 and 2 as an example, the heat sink according to the present invention can restrain the pressure loss of the coolant flowing in the heat sink and cause the coolant to flow uniformly in a coolant passage. Therefore, the heat sink can improve the cooling efficiency of the heat sink. Moreover, the heat sink can restrain an increase of the volume in the depthwise direction (the depth of the U turn portion of the coolant passage in the heat sink) as much as possible, and enable compactification of the heat sink. Therefore, it is possible to obtain a heat sink which is uniform in temperature distribution, smaller in required space and low in pressure loss.

The present invention relates to fluid passage or passages conveying a coolant of the heat sink. Variation and modification of the construction are possible in the range in which the effect(s) of the present invention is not impaired. For example, it is possible to form a heat signal having fluid passages similar to the coolant passages 2 and 3 and the connecting passage 4, by partitioning the inside of a tubular member.

Furthermore, as shown in FIG. 4, a plurality of fins 9, if formed in or on fluid passages of the coolant passages 2 and 3 and the connecting passage 4, are effective for improving the cooling efficiency, by transferring heat from the component to be cooled through the fins 9 to the coolant.

The geometry of the connecting passage in the heat sink according to the present invention is not limited to the U turn shape as in the embodiments, but applicable to portions where the direction of the flow of the coolant is changed. The coolant passages and the connecting passage may be prepared as separate members or may be integral parts of an integral member of the coolant passages and the connecting passage.

EXPLANATION OF REFERENCE NUMERALS

-   1, 10 . . . heat sink -   2, 3 . . . coolant passages -   4, 11 . . . connecting passage -   7 . . . parting portion -   8 . . . component to be cooled -   9 . . . fin 

1-5. (canceled)
 6. A heat sink comprising: two or more coolant passages arranged nonlinearly to convey a coolant for heat exchange with a heat of a component to be cooled; and a connecting passage connecting the coolant passages; wherein a fluid passage of the connecting passage on an inflow side to which a coolant flows in is enlarged in a direction of a height of a cross section, as compared with the coolant passage connected with the fluid passage on the inflow side; and the fluid passage of the connecting passage is decreased in size in the direction of the height of the cross section toward an end portion of the connecting passage on an outflow side from which the coolant flows out from the connecting passage.
 7. The heat sink as recited in claim 6, wherein the height of the cross section of the fluid passage of the connecting passage on the inflow side to which the coolant flows in is increased gradually from a connection portion between the connecting passage and the coolant passage connected with the fluid passage on the inflow side.
 8. The heat sink as recited in claim 6, wherein the fluid passage of the connecting passage located on an extension of the coolant passage connected with the fluid passage on the inflow side is made substantially equal in cross section to the coolant passage connected with the fluid passage on the inflow side, and curved in a direction of a height of the cross section of the connecting passage.
 9. The heat sink as recited in claim 6, wherein the coolant passage connected with the fluid passage on the inflow side and the coolant passage connected with the fluid passage of the connecting passage on an outflow side from which the coolant flow out from the connecting passage are arranged in parallel to each other.
 10. The heat sink as recited in claim 6, wherein the coolant passages are arranged so that the component to be cooled is provided on an upper surface of each of the coolant passages. 